It has been heretofore proposed that loading and unloading mechanisms be provided for placing and removing workpieces on a machine tool such as the chuck of a lathe so that various functions can be performed on the workpiece and thereafter unloading the workpiece.
In one type of mechanism heretofore used, mechanical clamping arms are pivotally mounted and movable toward and away from the workpiece to grip and release the workpiece. A problem with such mechanisms is that if the diameter of the workpiece changes, the position of the centerline of the workpiece changes.
Accordingly, the present invention is directed to a loading and unloading system that obviates this problem.
In accordance with the invention, a loader-unloader system is provided for loading and unloading workpieces in a machine tool wherein each workpiece is held in position for rotation about a longitudinal axis during which various machine operations may be performed on the tool. The system comprises a loading chute adapted to deliver articles in succession to a loading position and an unloading chute adapted to receive workpieces. A loader-unloader assembly is provided adjacent the chutes and comprises a track extending along an axis parallel to the longitudinal axis of the machine, a trolley movable along the track means, and means for moving the trolley back and forth along the track means. A loader clamping head assembly is mounted on the trolley, and an unloader head assembly is mounted on the trolley. Each assembly includes a head for gripping a workpiece and is mounted on the trolley for swinging movement into and out of position adjacent the machine tool and for reciprocating movement toward and away from the axis of the machine tool. Each assembly includes fingers on each head that are movable in a linear path toward and away from one another to grip and release a workpiece. One of the assemblies has a head rotatable to remove a workpiece from the machine, rotate it 180.degree. and return the workpiece to the machine for further machining.